This invention relates to a switching regulator, and in particular to a switching regulator employing a delta-sigma modulation scheme as a switching scheme.
Recently, switching regulators are widely employed as power-supply devices in various types of electronic equipment for the reason that the switching regulators are advantageous in terms that they are small in size and have high efficiency, and can be highly integrated. These switching regulators usually employ a PWM modulation scheme as their switching scheme, whereas the use of a delta-sigma modulation scheme has been increased as well.
A power-supply device is required to detect an instantaneous drop in power supply voltage (instantaneous break) in order to protect a load supplied with power by the power-supply device and to protect the power-supply device itself.
Japanese Laid-Open Patent Publication No. 2009-118651 (Patent Document 1) describes a technology in which a voltage at an internal circuit power supply terminal (VDD) is monitored, and switching operation of a switching element is stopped once it is detected that the monitored voltage has dropped below a predetermined voltage.
Japanese Laid-Open Patent Publication No. 2009-100498 (Patent Document 2) describes a technology in which any instantaneous break in power supply voltage is detected by detecting that the ON time of a switching element has exceeded a predetermined value.